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Związki między temperaturą wody w energoaktywnej strefie Morza Bellingshausena a temperaturą powietrza na Stacji Arctowskiego

Styszyńska A.

Problemy Klimatologii Polarnej

1998

nr 8

25--46

The main task of this paper is to explain if there is an energy-active sea zone in the vicinity of the South Shetland Islands and the Antarctic Peninsula which controls changes in atmospheric circulation in this area. The analysis made by use of the data comprising information about mean monthly sea surface temperatures (later SST) and SST anomalies in 2 x 2° grids - GEDEX and data about mean monthly air temperatures taken at the Arctowski Station (Meteorological Yearbooks of the Arctowski Station). Common data spanned the period from January 1982 to April 1992. The first stage of this work was to find so called .active grids", i.e. grids of bigger influence of ocean surface on thermic regime of distant areas. In order to do that an analysis of changes in SST in parts of the South Ocean comprising the Bellingshausen Sea, the Drake Strait, the Scotia Sea and the boundary between the Scotia Sea and the Weddell Sea was carried out. The analysis resulted in a conclusion that three grids situated 80oW: 56°,60° and 64°S show the larger relation with the flow of air temperature at the Arctowski Station. There are synchronic and asynchronic correlations between SST anomalies and the air temperature in nominated grids of the Arctowski Station. The results of analysis of synchronic correlations have been presented in table l. Asynchronic correlations are of complicated nature and distributions. Most numerous simple correlations were reported to occur between the temperature at the Arctowski Station and SST Anomalies in grids [80°W, 64°S]. The largest correlations are those with anomalies occurring in January, February and March. They can be observed in the air temperature with 11-13 months delay. The combined correlations are multiple correlations between regression equation of synchronically occurring anomalies (AN) in those grids and the air temperature at the Arctowski Station (ARC) in consecutive months (1, 2, 3, ..., n, n + 1, n + 2); ARC_n = a + b AN[80.56]_n + c AN[80.60]_n + d AN[80.64]_n. Table 2 contains set of multiple correlation coefficients and those which are likely to be significant have been marked. It has been stated that SST anomalies at 800W in March correlate with monthly air temperatures at the end of summer the following year (February and March) at the Arctowski Station and with temperatures of the early and midwinter of the following year (May, June, July).The variation in SST anomalies in March explains 88% - 69% of variance of variation in the air temperature in June and in July of the following year at the Arctowski Station (fig. l). The response of the air temperature to the occurrence of SST anomalies in October at 800W is much faster - from one to five months. Large correlation between the air temperatures at the Arctowski Station and SST anomalies can be observed already in December of the same year and in January, March and April in the following year (fig. 2). The above stated facts lead to conclusion that the distribution of SST does not influence the flow of the air temperature in a continuous way. Future variations in the air temperature are influenced by the states of thermal field of water measured at crucial moments (the end of summer and the end of winter). They are the states, which later on are slowly modified by processes of radiation in-and off flow, wind chilling and dynamic processes active in the ocean (heat advection following the mass advection). Thus a thesis can be stated that the SST anomalies occurring in grids 56°, 600 and 64°S. 800W may serve as predictive values to work out long term prognosis of the air temperature at the Arctowski Station. These prognosis can be divided into "early" prognosis with 2-6 months' advance (equations 1-4) and "distant" prognosis with 11-18 months' advance (equations 5-8). The above mentioned equations explain about 91% to 52% of variations in the mean monthly air temperature at the Arctowski Station. The presented facts indicate that there really is energy-active zone in the Bellingshausen Sea. Chapter 6 in 4 points shows how the hypothetical mechanism works. It can be understood and explained in a similar way as in case of the Labrador Sea and the New Foundland region (Marsz 1997). The analysis of synchronic statistical correlations between the air temperature at the Arctowski Station and the distribution of SST anomalies at 80°W indicates, among others, the presence of the mechanism described in Chapter 6. Such correlations have been analysed and discussed in a detailed way for April (fig. 3, equations 9 and l0) and for July (fig. 4, equation 11).